<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div{
            width: 100px;
            border: 1px solid #000;
        }
        #colleague{
            display: none;
        }
    </style>
</head>
<body>
    <div>
        家人
    </div>
    <div>
        同学
    </div>
    <div onclick="funC()">同事</div>
    <div id="colleague">
        <div>张院长</div>
        <div>李国军</div>
        <div>庆贺</div>
    </div>
    <div>1111</div>
</body>
    <script>
        function funC(){
            var obj = document.getElementById("colleague")
            if (obj.style.display == "none"){
                obj.style.display = "block"
            }else {
                obj.style.display = "none"
            }
        }
    </script>
</html>